This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The Human Microbiome Project (HMP) has identified many sites in the human body where diverse communities of commensal ("friendly") microbiota exist;and a growing literature suggests that variations in these communities are related to short- and long-term health. One site not on the HMP list is the lactating breast, although the presence of commensal microbiota in the mammary gland and milk would likely have significant impacts the health of both the mother and child. Our preliminary data demonstrate that milk from lactating women does, in fact, have a rich and diverse microbiome. The breastfed infant, therefore, receives not only the nutrients and other biologically active components from milk but also an inoculum of bacteria. As such, it is possible that some of the health benefits of breastfeeding, such as reductions of risk for obesity and allergy in the infant and breast cancer in women, are related to variations in milk/mammary microbiota. We propose to extend our preliminary analysis of this unique microbiome to investigate changes (or lack thereof) during the first 4 mo postpartum and relationships with microbiota found on breast epithelia as well as the infant's gastrointestinal tract (mouth and feces). This will allow us to determine the corresponding changes in each site and possible source(s) of the bacteria. Additionally, we will relate the richness and diversity of the milk/mammary microbiome with nutrients in milk, maternal dietary intake, parity, delivery mode, and other anthropometric data such as maternal body mass index. Long-term public health benefits gleaned from these studies may ultimately extend to a reduction in rates of childhood and adult obesity as well as breast disease (e.g., mastitis and breast cancer).